1. Field of the Invention
The present invention relates to a tire configuration control method, a holding apparatus for post cure inflation, and a post cure inflation apparatus.
2. Description of the Related Art
The uniformity characteristics of a tire are determined by a force variation in a radial direction of the tire (i.e., a weighing direction of the tire) (RFV: Radial Force Variation), a force variation in a lateral direction of the tire (LFV: Lateral Force Variation), and a force variation in a tangential direction of the tire (TFV: Tangential Force Variation). RFV, LFV, and TFV each having lower values are evaluated to be able to maintain superior uniformity characteristics. Further, since excessive force is generated at a circumferential portion which protrudes outwardly from the tire, RFV of uniformity characteristics is correlated with such ununiformity of size that may occur in the radial direction of the tire (RR: radial runout).
Conventionally, in order to correct uniformity characteristics of a tire by increasing RFV, the reducing of RR of the tire has been carried out.
In order to reduce RR of a tire, a method in which the aforementioned protruding portion of the tire is abraded is employed. As an apparatus for which this method has been applied, for example, a post cure inflation apparatus (i.e., a post cure inflator which is referred to as PCI, hereinafter) has been proposed in which the outer diameter of a tire is measured by a tire diameter sensor, and a portion having a larger outer diameter of the tire is abraded by an outer diameter buffing apparatus, during the steps after vulcanization (Post Cure Inflation which is referred to as PCI, hereinafter) in which a tire after vulcanization (post cure) is maintained constant so as to stabilize the configuration of the tire (Japanese Patent Application Laid-Open (JP-A) No. 3-153319).
Further, there is also provided a method in which uniformity characteristics can be improved not by abrading a tire but by deforming permanently a carcass reinforcing member of a tire after vulcanization at an ordinary temperature (Japanese Patent application Laid-open (JP-A) No. 6-507858). As an apparatus to which this method has been applied, an apparatus in which a tire product is previously tested for its uniformity characteristics, and a portion of the tire at which uniformity characteristics are needed to be controlled is specified, and a relatively high inflation pressure is applied to the tire for a predetermined period of time in a state in which this portion is restrained by a restraining ring. By this apparatus, the tire is inflated until it has the pressure which is equal to or greater than a recommended operational pressure of the tire, the portion of the carcass reinforcing member is pulled, and permanent elongation is thereby generated so that uniformity characteristics of the tire can be improved.
However, in the above-described method in which a tire is abraded, the appearance/the quality of the tire may deteriorate by abrasion. Further, there arises a problem in that dust is caused by abrade so that workshops may be polluted. Moreover, in the method in which a portion of the carcass reinforcing member is deformed permanently without abrading the tire, there may be a case in which the pressure needed for generating permanent deformation on a portion of the carcass reinforcing member is extremely large due to the type/the physical properties of the carcass reinforcing member(s). As a result, due to such excessive pressure, a tire may be broken.